1. Field of the Invention
The present invention relates to a photolithography technique, and more particularly relates to a technique for determining an exposure condition for a process of an exposure.
2. Description of the Background Art
For a process of an exposure using a photolithography technique in manufacture of semiconductor devices, a mask in which a predetermined pattern is written is employed, for example. FIG. 8 is a flow chart illustrating conventional processes performed before a mask which is newly made using either a new pattern or existing patterns (hereinafter, referred to as a xe2x80x9cnew maskxe2x80x9d) is actually applied to manufacture of semiconductor devices in lots. According to the conventional processes, a test exposure which actually employs an aligner is performed every time a new mask is made, in order to determine an exposure condition (an optimum exposure dosage and an optimum focus offset) for using every new mask.
The test exposure includes a manual operation in which an exposure is actually performed using an aligner, which requires much labor. Also, aligners vary in properties such as an aberration thereof. Accordingly, aspects to be considered for determining an exposure condition vary among aligners to be respectively used in conjunction with various new masks, to further complicate processes for determining an exposure condition. As a result, much labor as well as much time has been taken until a mask as made is actually applied to manufacture of semiconductor devices in lots.
It is an object of the present invention to provide an exposure condition calculation system which eliminates a need of complicated processes for verifying the exposure condition, and makes it possible to obtain an exposure condition determined in accordance with properties of each aligner.
According to the present invention, an exposure condition determination system includes a data base and an exposure condition determination unit. The database stores a first information about a past exposure. The exposure condition determination unit determines an exposure condition suitable for a new mask which is newly made, based on the first information stored in the database and a second information about an exposure using the new mask.
The exposure condition determination unit reflects the first information in determination of an exposure condition. This makes it possible to obtain an exposure condition suitable for the new mask without performing complicated processes for verifying the exposure condition. Further, the first information includes information about properties of an aligner, and the second information includes information indicating an aligner to be employed for the exposure using the new mask. As a result, it is possible to obtain an exposure condition determined in accordance with properties of each aligner.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.